localhost api 请求的 Http 失败响应：0 未知错误 - Angular

Question

我正在尝试从我的 Angular 应用程序创建到我的 Java Jetty 后端的通信。当我尝试执行我的请求时，我收到以下错误：

我在客户端的代码：（Angular 7.2.1）。我还使用 HttpInterceptor 进行应该有效的身份验证。我也在开发模式下使用ng serve.

@Injectable({
    providedIn: 'root'
})
export class NgHydrantService {

    constructor(private http: HttpClient) {
    }
  
    public register(entity: IEntityDescription): Observable<StandardResponsePacket> {
        let packet = new RegisterEntityRequestPacket(entity);
        return this.http.post(this._apiUrl, packet.toJson())
            .pipe(
                map(value => {
                    console.log('register result:', value); //<-- never executed
                    return <StandardResponsePacket>HydrantPackage.fromJson(value)
                })
            );

    }
}

//The interceptor
intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
        // add authorization header with basic auth credentials if available
        if (this.user != null) {

            const clonedRequest = request.clone({
                headers: request.headers.set('Authorization', `Basic ${this.user.getAuth()}`)
                                        .set('Accept','application/json')
            });
            //This debug line works and looks good!
            console.log('NgHydrantAuthInterceptor#intercept', clonedRequest);
            return next.handle(clonedRequest);
        }

        return next.handle(request);
    }

我在服务器端的代码：（Jetty-9.4.14.v20181114）在本地主机上运行。

public final class PacketHandler extends AbstractHandler
{
  @Override
  public void handle( String target,
                    Request baseRequest,
                    HttpServletRequest request,
                    HttpServletResponse response ) throws IOException
  {
    try
    {
        // Declare response encoding and types
        response.setContentType( "application/json; charset=utf-8" );
        // Enable CORS
        response.addHeader("Access-Control-Allow-Origin", "*");
        response.addHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, DELETE, HEAD");
        response.addHeader("Access-Control-Allow-Headers", "X-PINGOTHER, Origin, X-Requested-With, Content-Type, Accept");
        response.addHeader("Access-Control-Max-Age", "1728000");
        //... more stuff
    }
    finally
    {
        // Inform jetty that this request was handled
        baseRequest.setHandled( true );
    }
  }
}

我检查的东西：

• 在研究期间，有些人引用了 CORS 的问题（这就是我在服务器端代码中添加标头条目的原因）
• Postman 中的相同请求没有任何问题
• 服务器端没有日志

我的问题是关于在开发过程中从我的服务器获得响应的可能解决方案。

Answer 1

您可以按照以下链接中的步骤进行操作吗？ https://www.html5rocks.com/en/tutorials/cors/ 如需快速解决方案，请在 chrome 中添加以下插件 https://chrome.google.com/webstore/detail/allow-控制允许-origi/nlfbmbojpeacfghkpbjhddihlkkiljbi?hl=en